1. Field of the Invention
The present invention relates to a thermosetting resin material. The thermosetting resin material of the invention is preferably used for various uses, for example, friction materials, molding materials, machine parts, structural members, structural adhesives, and the like.
2. Background Art
Thermosetting resins having a dihydrobenzoxazine ring are excellent in heat resisting decomposition characteristic in both atmospheres of an oxidizing atmosphere (for example, in atmospheric air) and an inert atmosphere (for example, in nitrogen gas) and have an advantage of not generating by-products at thermosetting time, but have a drawback such that thermosetting takes time. Therefore, shortening of thermosetting time has been tried by the addition of thermosetting resins such as phenol resins and polyimide resins, but physical properties are liable to be influenced by the thermal decomposition characteristic of the resins to be added.
For example, a thermosetting resin composition containing a thermosetting resin having a dihydrobenzoxazine ring and a novolak type phenol resin is disclosed in Patent Document 1. However, heat resisting decomposition characteristic of novolak type phenol resin is excellent in an inert atmosphere but inferior in an oxidizing atmosphere, so that the thermosetting resin composition is insufficient in heat resisting decomposition characteristic in an oxidizing atmosphere.
On the other hand, polyimide resin is excellent in heat resisting decomposition characteristic in an oxidizing atmosphere, but inferior in an inert atmosphere, so that a thermosetting resin composition containing a thermosetting resin having a dihydrobenzoxazine ring and a polyimide resin has a drawback such that heat resisting decomposition characteristic in an inert atmosphere is insufficient.
As resins excellent in heat resisting decomposition characteristic in both atmospheres of an oxidizing atmosphere and an inert atmosphere, condensed polycyclic aromatic hydrocarbon resins (generally called as COPNA resins) are known. For example, a thermosetting resin obtained by introduction of a phenolic nucleus into the molecule of a condensed polycyclic aromatic hydrocarbon resin is disclosed in Patent Document 2, but hexamethylenetetramine (hexamine) and an acid catalyst are necessary for thermosetting of the thermosetting resin, and a by-product is generated at the time of thermosetting, so that there are problems in the points of environmental aspect and stability of quality.
Further, when an acid catalyst is used as a setting agent, problems arise such as occurrences of corrosion and rust of a molding apparatus of the thermosetting resin.
[Patent Document 1] JP-A-09-272786
[Patent Document 2] JP-A-08-145098